Lies and politics

How come we allow politicians and journalists to lie? We have a society where economic crime is punished harder than violence, because we realise that economic crime can undermine societies. We need to be able to trust in the system, for the economy to work. But why then should we not do the same for lies? Lies, especially when uttered by politicians, are just as destructive for society and trust. I would argue it is maybe the most destructive and dangerous thing for democracy I can think of. Why do we not give fines to politicians that lie?

One argument could be that it is too hard to determine when something is a lie, when someone was simply misinformed, misspoke, or just misunderstood the facts. But then why can we do it for things like punishing people for inciting violence? Couldn't we have an nonpartisan "Department of lies", like the police and courts. Someone tasked with "suing" politicians and newspapers for lies. Someone that would investigate and give a fine if you were found guilty. If the fines went to the state treasury, there would not be much incentive for it to go corrupt.

Another solution might be an NGO that was tasked with simply mapping the lies of politicians, and then ranking them on an official public website, where everyone could see who talked the most shit.